The present invention relates to a disk drive such as an optical video disk player or a compact disk player, and a playback method adapted for a disk drive capable of playing back a compact disk, including a DC-V, or an optical video disk, or both.
Referring to FIG. 1, a conventional disk drive of a first type includes a pickup 2 having an objective lens 3. A disk 1, which stores data on both sides, is rotatably driven and supported by a drive and support mechanism 4 including a spindle, a spindle motor, a turntable, and a clamper. A portion 6 of the mechanism 4 is located above the disk 1. The spindle is disposed near the center of the disk 1. That is, for ease of illustration, only approximately one-half of the disk 1 is shown in FIG. 1.
When the lower side of the disk 1 is played back, the pickup 2 is first brought close to the innermost track on the disk. At this time, the objective lens 3 is located at a portion of the pickup which is radially inward with respect to the disk in order to prevent the lens from bearing against the drive and support mechanism 4. That is, the lens 3 is located at a radially inner half of the pickup.
The pickup 2 is driven radially (from left to right as viewed in FIG. 1) with respect to the disk 1 by a carriage motor (not shown) to play back the disk from the innermost track to the outermost track. That is, the pickup 2 is mounted on a carriage (not shown) which is propelled by the carriage motor.
After the pickup 2 is moved outside the circumference of the disk 1, it is reversed about an axis 5 perpendicular to the direction in which the pickup 2 is moved by the carriage motor, so that the pickup is now above the disk 1. The pickup 2 is then moved into a given position, near the center of the disk, as represented by the dashed lines in FIG. 1. Then, the pickup 2 is moved radially outwardly from that position to play back the upper side of the disk 1.
In this first conventional disk player, the pickup 2 is reversed in this way about the axis 5 perpendicular to the direction in which the pickup is translated by the carriage motor. Therefore, when the pickup 2 is reversed, the radially outer side (with respect to the disk) of the pickup which was placed on the underside is located on the radially inner side and may collide with the upper portion 6 of the mechanism 4. This possibility of collision is especially great in the case of a disk drive capable of playing back compact disks with relatively small radii. To avoid such a collision, various apparatus have been proposed. For example, it has been proposed to place the lens 3 at the radial center of the pickup 2 to form a symmetrical structure, and/or to specially shape the upper portion 6. As a result of the symmetrical structure, the pickup 2 has a relatively great height dimension. Further, distance L between the outer circumference of the disk 1 and the outer circumference of the arc circumscribed by the pickup 2 when it is reversed must be large to enable reversing of the pickup. In addition, the output cord from the pickup 2 must be relatively long, and it is cumbersome to handle it without tangling or the like as the pickup 2 moves.
FIG. 2 shows the structure of a second conventional disk drive which includes a spindle motor 111 that rotates a turntable 112. A clamper 113 clamps a disk 1 against the turntable 112. A lower guide bar 115 is located below the disk 1 and guides sliding movement of a slider 7 that shifts radially with respect to the disk. An upper guide bar 116 is disposed above the disk. A gear 8 which is mounted to the slider 7 is in mesh with a substantially U-shaped rack 9. When a slider motor (not shown) mounted on the slider 7 is driven, the gear 8 is rotated to cause the slider 7 to slide radially with respect to the disk 1. At this time, the sliding movement of the slider 7 is guided by the guide bar 5. A pickup 102 is installed on the slider 7 and moves radially together with the slider 7. Thus, signals recorded on the disk 1 are played back from the innermost track to the outermost track.
A tilt control mechanism is also mounted on the slider 7. Specifically, the pickup 102 is held on the slider 7 so as to be rotatable about a pin 212. When a driving mechanism 104 is actuated, the pickup 102 is rotated about the pin 212 to control the angle of the pickup with respect to the disk 1.
In this way, the lower side of the disk 1 is played back. When the upper side of the disk 1 is to be played back, the gear 8 is driven so that the slider 7 comes out of the lower guide bar 115. The slider 7 is then reversed while being guided by the rack 9, and fitted over the upper guide bar 116. The pickup 111 will thus face downward, i.e., toward the disk 1. The upper side is then played back and the angle of the pickup is controlled in the same manner as in the case where the lower side is played back.
In this second conventional disk drive, the tilt control mechanism is mounted on the slider 7 in addition to the above-mentioned other elements. Therefore, the total mass of the slider 7 and elements thereon is relatively large. This makes it difficult to rapidly drive the slider 7. In addition, an expensive, large-capacity slider motor is needed, and the whole apparatus thus becomes large. Another disadvantage of this disk drive is that the distance between the disk 1 and the pickup 2 varies if the disk is warped, since only the angle of the pickup 102 is adjusted.
Accordingly, the present invention is also intended to reduce the mass of the slider and its contents. Also, the angle of the slider to the disk is controlled. Further, the distance between the disk and the pickup is maintained constant.
Additionally, motor noise adversely affects the output signal from the pickup, because the slider motor is carried on the slider. Further, the feeder line to the slider motor moves with the slider and so it is cumbersome to handle the line.
A compact disk has only one recorded surface; no signals are recorded on the other surface. Since the pickup is usually disposed on one side (e.g. the lower side) of the turntable, a compact disk is loaded that the recorded surface sits on the turntable. If the disk is incorrectly loaded, i.e., the non-recorded surface is placed on the turntable, then the incorrect loading is detected, and the disk must be removed and reloaded. In the conventional disk player, playback is allowed only if a disk is loaded in such a way that the recorded surface faces downward. Therefore, the user must check the sides of the disk before it is loaded. If the user incorrectly inserts the disk for whatever the reason, the user will be required to remove the disk, flip it, and reload it. In view of the foregoing, the present invention has been made. The present invention is intended to play back the recording on a disk irrespective of how the disk is loaded.